Portastudio - Live Looping

I'm continuing with my goal of turning my Tascam Portastudio 424 into a live performance instrument.  A key step was to take a regular cassette tape and to turn it into a continuously looping tape.  At normal speed on the Portastudio, my loop tape gives about a 5 second loop.  In trying to use the Portastudio as a live instrument, I've been learning how to record to the loop tape and to play back from the loop tape all in real time.  As with any instrument, it takes time and practice to figure out the interesting techniques and effects that the instrument enables.  Below is a demo of what I've figured out so far.

Recording to Tape:  To record audio to tape, the Portastudio allows several different methods.  Which method you choose is driven by your needs.  Because I want to use it as a live looper, I'm hoping to find a method that causes the Portastudio to play back the recorded audio as a loop as soon as I finish recording recording it.  Ideally, this will happen with no break in the action.  While this is trivially easy on a digital looper like the Kaossilator, it is a little trickier on a tape-based machine, since live looping is not what this kind of tape-based machine is designed to do.

Punch-In/Punch-Out:  Luckily, the Portastudio is designed to allow you to easily toggle between record and play modes without stopping the tape.  This is the "punch-in"  / "punch-out" practice that allows one to, say, redo a guitar solo without affecting the guitar that was recorded just before and just after the solo.  When we use our loop tape instead of a normal tape, this means that we can hear our loops, then "punch-in" to overwrite all or part of the loop, and then "punch-out" to let the loop resume playing.  You start the process by simply hitting "play" on the Portastudio.  To "punch-in", you hit the Record button (or press the "punch-in/punch-out" footswitch, like I do in the video).  To "punch-out", you hit the Play button again (or press the footswitch again).  At no point do you hit Stop...it just keeps going continuously.

Input Setup:  The Portastudio can configure its inputs a number of ways.  To get the Portastudio to playback your newly-recorded audio as soon as you punch-out, you need to use the configuration shown in the pics below.  The key is that you setup your target track (in this case, Track 1) to record NOT what is directly plugged into Track 1, but instead to record whatever is on the master bus.  You do this by setting the Track 1 Input to "Mic/Line > L".  Here, it'll record whatever is on the left channel of the master bus.  Critically, when the Portastudio is not in record mode, this setting also causes the Portastudio to simply playback whatever is on that track.  This is how you get it to play back the audio (without any further action) as soon as you punch-out.

Overall Configuration To Record to Track 1 and then
Get Instant Playback of Loops After Punching-Out.

Detail view of input settings to record to Track 1 from the master bus and to get instant
playback after punching-out.  My input audio is from the black and red plugs on the
right, which are configured to inject it to the L-R on the master bus.

Cue Bus:  Once you get one track recorded, you'll want to listen to that track while you record the next tracks.  In normal operation, you'd just have those tracks play back their audio on the master bus.  But, once you configure Track 2 to record like we did for Track 1, it'll record everything on the master bus...including your already recorded audio on Track 1.  Bad.  So, what you do is silence the playback of Track 1 on the main bus (by pulling down the volume slider) and instead play Track 1 on the Cue Bus.  As long as your headphone (ie, the "Monitor" buttons) are set to Left+Right+Cue, you'll hear all of the audio nicely.  So, after recording each track to tape, silence it on the main bus and bring it up on the Cue Bus.  Now you're ready for the next Track!

Settings for the Cue Bus so that I hear all tracks via the Cue Bus,
except for Track 1, which was already set for the Master Bus.

Live Effects Loop:  Now we get tricky.  As you saw in the video, after I recorded four tracks onto my loop tape, I hooked up the Monotron Delay to be an effects box for the already-recorded audio.  I was able to selectively and dynamically send audio from different tracks to the Monotron for filtering and echo effects.  I did this by re-using the Cue Bus.  Once my tracks were all recorded, I did the opposite of what I described above -- I moved all of the tracks off the Cue Bus and put them all back onto the Master Bus.  I then set my headphones (ie, the "Monitor" buttons) to listen only to the Master Bus.  That way, I could selectively send channels to the Cue Bus (via the Tape Cue knobs shown above) without hearing it.  Interestingly, the mixed audio on the Cue Bus is available via the "Effects" jack on the back of the Portastudio.  Secretely, this output jack is a stereo output.  One channel is the Effects Bus (which, despite its name, is not helpful in this scenario) while the other channel is the Cue Bus.  So, I plug Cue Bus into the Aux In of my Monotron Delay.  I then leave the Monotron's output plugged into the Master Bus so that I can hear the echos.  Instant live effects!

Configuration of Portastudio to allow live effects using the Cue Bus.
Note that I did not use the Portastudio's Effects Bus, because it does
not allow 100% effected signal, some dry signal must always
be present.  Using the Cue Bus avoids this limitation.

So this is the best setup that I have found for doing live looping with the Portastudio.  The key with this method is that the tape never stops, so your groove can just keep on going.

Cassette Tape Loop

Over the weekend, after finishing up on my MIDI-to-Trigger converter, I got the idea to dig out my old Tascam Portastudio 4-track cassette recorder (from the early '90s!) and to see what kind of weird noise-hacking fun I could have with the old girl.  I had this vision that I could turn it into a monster multi-track tape delay machine with cool sound-on-sound looping.  Man, I was getting excited.  Before, before diving into modifications of the hardware, I decided to start a little more simply...I decided to start with making a tape loop from a cassette.  In the video below, you can see what I did and get a quick demo.  I got really lucky and ended up with a sweet saxophone loop.  Nice!

If you'd like to make your own cassette loop (for use in a normal cassette deck, or in a fancy 4-track cassette recorder), there are lots of videos and how-to pages on the internet.  While I found them helpful, I found that practice was the key.  In my photos below, I don't really shed any new light on the matter, but maybe you'll see something that isn't available elsewhere.

First, start with a cassette.  I started with an old one of mine that had material already on it.  If you're really good, you can purposely excerpt a piece of tape with an audio segment that you're purposely trying to loop.  I didn't have such high hopes.  I just grabbed a tape that was in the same box as my 4-track cassette recorder.  It was a cassette that originally had an Ani DiFranco album (that I recorded from CD probably around 1998).  I then re-purposed the cassette to record a jam session at a friend's house (Hi Paula!) in 2000 ("Alpine Music Fest").  Since I have all of that material elsewhere, I decided that this is a good tape to sacrifice for my experiments with making a cassette loop.

An old cassette.  It once was Ani DiFranco.  Then it was re-used to record
a jam session.  "Alpine Music Fest 2000".

Below, you can see the cassette after I opened it up.  With it open, I cut the tape and removed the tape from the two white plastic spools.

I opened up the cassette to remove the long spools of tape.

I then started trying to make my tape loops.  As mentioned later, it took me four tries to get one that worked.  The photo below is the configuration that eventually worked...I used both plastic spools.  With both spools in place, I cut a segment of tape that was approximately correct in length, including a small amount of overlap...about half an inch (~1 cm) is probably sufficient, though you might want a little more overlap just to make it easier to handle.

I cut a short segment that would fit once around.

Then, I got out my adhesive tape.  You want something really thin, so I tried my generic brand and my name brand tapes.  For my first two trials (both failures), I used the name brand "Scotch" tape shown on the right.  For my third trial (also a failure) and for my fourth trial (a success), I used the store brand.  The store brand did seem better in this case...the Scotch brand was "matte finish", which meant it was thicker.  No good.  Go for the thin (but sticky!) stuff.

The cheap clear adhesive tape on the left worked much better
than the "fancy" adhesive tape on the right.

Once you've picked the tape that you want to use, you need to cut a *really* small piece.  It should be more narrow than the audio tape...and it shouldn't be too long.  You can see my piece of tape in the photo below.

I then cut the smallest piece of adhesive tape ever.

Next is the really tricky part.  You need to use the little piece of adhesive tape to splice together the ends of the audio tape.  While it's OK to have the ends of the audio tape overlap, it is very important that they are align straight.  If you don't have a "splicing block" (I don't have one), then this is where you just need to try it and practice.  It was really hard at first.  Then, I got a system that worked really well for me.  You can see the results below.

I used the little piece of adhesive tape to splice the audio tape it into
a single loop.  It ended up being about 5 seconds long.

The only thing wrong with the photo above  is that the tape is too tight.  When it didn't work (at first), I tried loosening the tape a little bit.  How?  Well, if you look closely down by each one of the little white rollers, you'll see that the tape goes around a thin dark-plastic post.  To make my tape loop a little looser, I pulled up the tape and allowed it to NOT pass around one of those posts.  This was just the amount of slack that it needed.  It worked!  Yay!

To finish the loop, you can use your scissors to trim away any audio tape that overlaps at the splice.  You don't need to get it perfect, but it is good to minimize the overlapping tape.  Then, put the cover back on the cassette and screw it back together.  Oh, and then rename the cassette.  In my case, this is its third name!

Here's the re-assembled cassette.  Ani DiFranco  and the Alpine Music Fest
 have now become a loop tape!

Now it's ready to be put in your cassette deck and played.  If you're like most people, your first bunch of trials won't work.  But if you keep trying, you'll get there.  As you can see in my video, I had a cool loop already recorded onto my loop tape.  Maybe you'll get lucky, too!

With excitement, I popped it into my 4-track cassette recorder and gave it a listen.
It didn't work.  The tape wouldn't move.  So I tried again.  And again.  And again.
On my fourth attempt, though, it worked great!

My next steps are to record some droning sounds on the four different tracks so that I can dynamically mix them together in a moody way.  I'm thinking that it will sorta be like my Kaossilator Pro (which is built to have four independent loops)...except the tape-based loop will be dirty sounding and not clean like the Kaossilator.  Hopefully, it'll be dirty in a good way.

After that, my plan is to see if I can defeat the erase head on the Portastudio so that I can attempt sound-on-sound layered recording.  Again, it'll be like the Kaossilator (which does sound-on-sound) except the Portastudio can add all of the sound mangling artifacts that come with audio cassettes.  Here I'm particularly interested in what happens when you overload the tape (ie, write on it many times without erasing) and what happens when you bounce back and forth between tracks so many times that the generational losses become dominant.  This could be seriously fun!

Do any of you have experience with tape loops or with hacking cassette decks?

Follow-Up: I show how to defeat the Erase Head here.

Follow-Up: I use my Tascam 4-track as a live-looping instrument here.